fix(codemode): preserve collection value identity

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/client/src/effect/api/api.ts

@@ -154,6 +154,7 @@ export type Endpoint4_12Input = {
   readonly text: Endpoint4_12Request["payload"]["text"]
   readonly description?: Endpoint4_12Request["payload"]["description"]
   readonly metadata?: Endpoint4_12Request["payload"]["metadata"]
+  readonly resume?: Endpoint4_12Request["payload"]["resume"]
 }
 export type Endpoint4_12Output = EffectValue<ReturnType<RawClient["server.session"]["session.synthetic"]>>
 export type SessionSyntheticOperation<E = never> = (input: Endpoint4_12Input) => Effect.Effect<Endpoint4_12Output, E>
@@ -439,8 +440,14 @@ export type Endpoint10_0Input = { readonly location?: Endpoint10_0Request["query
 export type Endpoint10_0Output = EffectValue<ReturnType<RawClient["server.mcp"]["mcp.list"]>>
 export type ServerMcpListOperation<E = never> = (input?: Endpoint10_0Input) => Effect.Effect<Endpoint10_0Output, E>
 
+type Endpoint10_1Request = Parameters<RawClient["server.mcp"]["mcp.resource.catalog"]>[0]
+export type Endpoint10_1Input = { readonly location?: Endpoint10_1Request["query"]["location"] }
+export type Endpoint10_1Output = EffectValue<ReturnType<RawClient["server.mcp"]["mcp.resource.catalog"]>>
+export type ServerMcpCatalogOperation<E = never> = (input?: Endpoint10_1Input) => Effect.Effect<Endpoint10_1Output, E>
+
 export interface ServerMcpApi<E = never> {
   readonly list: ServerMcpListOperation<E>
+  readonly catalog: ServerMcpCatalogOperation<E>
 }
 
 type Endpoint11_0Request = Parameters<RawClient["server.credential"]["credential.update"]>[0]

packages/client/src/effect/generated/client.ts

@@ -209,11 +209,17 @@ type Endpoint4_12Input = {
   readonly text: Endpoint4_12Request["payload"]["text"]
   readonly description?: Endpoint4_12Request["payload"]["description"]
   readonly metadata?: Endpoint4_12Request["payload"]["metadata"]
+  readonly resume?: Endpoint4_12Request["payload"]["resume"]
 }
 const Endpoint4_12 = (raw: RawClient["server.session"]) => (input: Endpoint4_12Input) =>
   raw["session.synthetic"]({
     params: { sessionID: input["sessionID"] },
-    payload: { text: input["text"], description: input["description"], metadata: input["metadata"] },
+    payload: {
+      text: input["text"],
+      description: input["description"],
+      metadata: input["metadata"],
+      resume: input["resume"],
+    },
   }).pipe(Effect.mapError(mapClientError))
 
 type Endpoint4_13Request = Parameters<RawClient["server.session"]["session.shell"]>[0]
@@ -529,7 +535,12 @@ type Endpoint10_0Input = { readonly location?: Endpoint10_0Request["query"]["loc
 const Endpoint10_0 = (raw: RawClient["server.mcp"]) => (input?: Endpoint10_0Input) =>
   raw["mcp.list"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError))
 
-const adaptGroup10 = (raw: RawClient["server.mcp"]) => ({ list: Endpoint10_0(raw) })
+type Endpoint10_1Request = Parameters<RawClient["server.mcp"]["mcp.resource.catalog"]>[0]
+type Endpoint10_1Input = { readonly location?: Endpoint10_1Request["query"]["location"] }
+const Endpoint10_1 = (raw: RawClient["server.mcp"]) => (input?: Endpoint10_1Input) =>
+  raw["mcp.resource.catalog"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError))
+
+const adaptGroup10 = (raw: RawClient["server.mcp"]) => ({ list: Endpoint10_0(raw), catalog: Endpoint10_1(raw) })
 
 type Endpoint11_0Request = Parameters<RawClient["server.credential"]["credential.update"]>[0]
 type Endpoint11_0Input = {

packages/client/src/promise/generated/client.ts

@@ -87,6 +87,8 @@ import type {
   IntegrationAttemptCancelOutput,
   ServerMcpListInput,
   ServerMcpListOutput,
+  ServerMcpCatalogInput,
+  ServerMcpCatalogOutput,
   CredentialUpdateInput,
   CredentialUpdateOutput,
   CredentialRemoveInput,
@@ -538,7 +540,12 @@ export function make(options: ClientOptions) {
           {
             method: "POST",
             path: `/api/session/${encodeURIComponent(input.sessionID)}/synthetic`,
-            body: { text: input["text"], description: input["description"], metadata: input["metadata"] },
+            body: {
+              text: input["text"],
+              description: input["description"],
+              metadata: input["metadata"],
+              resume: input["resume"],
+            },
             successStatus: 204,
             declaredStatuses: [404, 400, 401],
             empty: true,
@@ -892,6 +899,18 @@ export function make(options: ClientOptions) {
           },
           requestOptions,
         ),
+      catalog: (input?: ServerMcpCatalogInput, requestOptions?: RequestOptions) =>
+        request<ServerMcpCatalogOutput>(
+          {
+            method: "GET",
+            path: `/api/mcp/resource`,
+            query: { location: input?.["location"] },
+            successStatus: 200,
+            declaredStatuses: [401, 400],
+            empty: false,
+          },
+          requestOptions,
+        ),
     },
     credential: {
       update: (input: CredentialUpdateInput, requestOptions?: RequestOptions) =>

packages/client/src/promise/generated/types.ts

@@ -856,17 +856,26 @@ export type SessionSyntheticInput = {
     readonly text: string
     readonly description?: string | null
     readonly metadata?: { readonly [x: string]: JsonValue }
+    readonly resume?: boolean | null
   }["text"]
   readonly description?: {
     readonly text: string
     readonly description?: string | null
     readonly metadata?: { readonly [x: string]: JsonValue }
+    readonly resume?: boolean | null
   }["description"]
   readonly metadata?: {
     readonly text: string
     readonly description?: string | null
     readonly metadata?: { readonly [x: string]: JsonValue }
+    readonly resume?: boolean | null
   }["metadata"]
+  readonly resume?: {
+    readonly text: string
+    readonly description?: string | null
+    readonly metadata?: { readonly [x: string]: JsonValue }
+    readonly resume?: boolean | null
+  }["resume"]
 }
 
 export type SessionSyntheticOutput = void
@@ -2478,6 +2487,36 @@ export type ServerMcpListOutput = {
   }>
 }
 
+export type ServerMcpCatalogInput = {
+  readonly location?: {
+    readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+  }["location"]
+}
+
+export type ServerMcpCatalogOutput = {
+  readonly location: {
+    readonly directory: string
+    readonly workspaceID?: string
+    readonly project: { readonly id: string; readonly directory: string }
+  }
+  readonly data: {
+    readonly resources: ReadonlyArray<{
+      readonly server: string
+      readonly name: string
+      readonly uri: string
+      readonly description?: string
+      readonly mimeType?: string
+    }>
+    readonly templates: ReadonlyArray<{
+      readonly server: string
+      readonly name: string
+      readonly uriTemplate: string
+      readonly description?: string
+      readonly mimeType?: string
+    }>
+  }
+}
+
 export type CredentialUpdateInput = {
   readonly credentialID: { readonly credentialID: string }["credentialID"]
   readonly location?: {
@@ -5508,6 +5547,14 @@ export type EventSubscribeOutput =
       readonly location?: { readonly directory: string; readonly workspaceID?: string }
       readonly data: { readonly server: string }
     }
+  | {
+      readonly id: string
+      readonly created: number
+      readonly metadata?: { readonly [x: string]: unknown }
+      readonly type: "mcp.resources.changed"
+      readonly location?: { readonly directory: string; readonly workspaceID?: string }
+      readonly data: { readonly server: string }
+    }
   | {
       readonly id: string
       readonly created: number

packages/client/test/promise.test.ts

@@ -50,6 +50,29 @@ test("exposes every standard HTTP API group", () => {
   expect(Object.keys(client.project)).toEqual(["list", "current", "directories"])
 })
 
+test("MCP resource catalog uses the public HTTP contract", async () => {
+  let request: Request | undefined
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async (input) => {
+      request = input instanceof Request ? input : new Request(input)
+      return Response.json({
+        location: { directory: "/tmp/project", project: { id: "proj_test", directory: "/tmp/project" } },
+        data: {
+          resources: [{ server: "docs", name: "Readme", uri: "docs://readme" }],
+          templates: [{ server: "docs", name: "File", uriTemplate: "docs://{path}" }],
+        },
+      })
+    },
+  })
+
+  const result = await client["server.mcp"].catalog({ location: { directory: "/tmp/project" } })
+
+  expect(result.data.resources[0]?.uri).toBe("docs://readme")
+  expect(request?.method).toBe("GET")
+  expect(request?.url).toBe("http://localhost:3000/api/mcp/resource?location%5Bdirectory%5D=%2Ftmp%2Fproject")
+})
+
 test("file.read returns binary content from the public HTTP contract", async () => {
   let request: Request | undefined
   const client = OpenCode.make({

packages/codemode/README.md

@@ -241,7 +241,7 @@ CodeMode executes a deliberately bounded JavaScript subset. It supports:
 - `if`, conditional expressions, `switch`, `for`, `for...of` (arrays, strings, Maps, Sets, including assignment-form destructuring such as `for ([key, value] of entries)`), `for...in` (own keys of plain objects, index strings of arrays, and namespace/tool names of `tools` references - anything else is an error suggesting `for...of` or `Object.keys`, rather than real JS's surprising behavior of indices for strings and zero iterations for Maps/Sets), `while`, and `do...while`.
 - Arrow functions and function declarations with closures, defaults, rest parameters, and destructuring.
 - Optional chaining, nullish coalescing, templates, spread (arrays, strings, Maps, Sets), and `try`/`catch`.
-- Common array, string, number, `Object`, `Math`, and `JSON` operations. Mutating array methods include `push`/`pop`/`shift`/`unshift`/`splice` (removes in place and returns the removed elements)/`fill`/`copyWithin`; array `keys`/`values`/`entries` return **arrays** (matching the Map/Set convention) and work with `for...of` and spread. String methods include `localeCompare` (locale/options arguments ignored), `normalize`, and the `trimLeft`/`trimRight` aliases. `Object.keys` also accepts arrays (index strings, as in JS) and tool references: `Object.keys(tools)` lists the top-level namespaces, including `$codemode`, and `Object.keys(tools.ns)` lists the names at that node (a callable tool enumerates as `[]`; an unknown path is an `UnknownTool` diagnostic). `Object.values`/`Object.entries` on a tool reference fail with a pointer at `Object.keys(tools)` and `tools.$codemode.search`.
+- Common array, string, number, `Object`, `Math`, and `JSON` operations, including primitive-number `valueOf`, the standard non-finite `Number` constants, and host-backed `Math.random`. Mutating array methods include `push`/`pop`/`shift`/`unshift`/`splice` (removes in place and returns the removed elements)/`fill`/`copyWithin`; array `keys`/`values`/`entries` return **arrays** (matching the Map/Set convention) and work with `for...of` and spread. String methods include `localeCompare` (locale/options arguments ignored), `normalize`, and the `trimLeft`/`trimRight` aliases. `Object.keys` also accepts arrays (index strings, as in JS) and tool references: `Object.keys(tools)` lists the top-level namespaces, including `$codemode`, and `Object.keys(tools.ns)` lists the names at that node (a callable tool enumerates as `[]`; an unknown path is an `UnknownTool` diagnostic). `Object.values`/`Object.entries` on a tool reference fail with a pointer at `Object.keys(tools)` and `tools.$codemode.search`.
 - `Date` - `Date.now()`/`Date.parse()`/`Date.UTC()`, `new Date(...)`, the getter methods, and date arithmetic/comparison via the time value. Dates stringify as ISO (`toString` included, for determinism across host timezones).
 - Regular expressions - `/literals/` and `new RegExp(...)` with `test`/`exec` (stateful `lastIndex` for `g`), plus string `match`/`matchAll`/`replace`/`replaceAll`/`split`/`search` with patterns. Match results are arrays carrying `index` and named `groups` as own properties (`input` is omitted). `replace` and `replaceAll` accept function replacers with captures, offset, input, and named groups; callbacks run sequentially, may await tool calls, and have their results coerced to strings. Invalid patterns, invalid flags, and missing-`g` calls fail with catchable errors that say what was wrong and how to fix it (escaping hints, the exact `/pattern/g` to write). Patterns run on the host engine, so pathological backtracking is bounded only by the execution timeout.
 - `Map` and `Set` - construction from entries/arrays/strings, `get`/`set`/`add`/`has`/`delete`/`clear`/`size`/`forEach`, and `keys`/`values`/`entries` returning **arrays** (not iterators).

packages/codemode/codemode.md

@@ -158,7 +158,7 @@ current omissions to implement, not intentional product boundaries.
 - [ ] Add `Object.is` after runtime method and tool references have stable identity semantics.
 - [ ] Add deterministic modern collection conveniences where they improve orchestration: `Object.groupBy`, Set
       composition methods, and `Array.prototype.toSpliced`.
-- [ ] Decide whether nondeterministic `Math.random` and iterable `Math.sumPrecise` belong in the runtime.
+- [ ] Decide whether iterable `Math.sumPrecise` belongs in the runtime.
 - [ ] Refine diagnostics so user throws, expected tool failures, unexpected host/tool defects, and genuine interpreter
       defects are distinguishable without leaking private causes.
 

packages/codemode/src/interpreter/runtime.ts

@@ -530,17 +530,29 @@ const invokeArrayStatic = (name: string, args: Array<unknown>, node: AstNode): u
       if (args[0] instanceof SandboxURLSearchParams) {
         return Array.from(args[0].params.entries(), ([key, value]) => [key, value])
       }
-      const source = boundedData(args[0], "Array.from input")
+      const source = args[0]
+      if (source instanceof SandboxPromise) {
+        throw new InterpreterRuntimeError(
+          "Array.from received an un-awaited Promise; await it before creating the array.",
+          node,
+          "InvalidDataValue",
+        )
+      }
       if (typeof source === "string") return Array.from(source)
       if (Array.isArray(source)) return [...source]
       if (
         source !== null &&
         typeof source === "object" &&
+        (Object.getPrototypeOf(source) === Object.prototype || Object.getPrototypeOf(source) === null) &&
         typeof (source as { length?: unknown }).length === "number"
       ) {
         return Array.from(source as ArrayLike<unknown>)
       }
-      throw new InterpreterRuntimeError("Array.from expects an array, string, Map, Set, or array-like value.", node)
+      throw new InterpreterRuntimeError(
+        "Array.from expects an array, string, Map, Set, or array-like value.",
+        node,
+        "InvalidDataValue",
+      )
     }
     default:
       throw new InterpreterRuntimeError(`Array.${name} is not available in CodeMode.`, node)
@@ -2005,6 +2017,9 @@ class Interpreter<R> {
         if (callable.namespace === "Object" && objectMethodsPreservingIdentity.has(callable.name)) {
           return invokeGlobalMethod(callable, args, node)
         }
+        if (callable.namespace === "Array" && (callable.name === "from" || callable.name === "of")) {
+          return invokeGlobalMethod(callable, args, node)
+        }
         return boundedData(invokeGlobalMethod(callable, args, node), `${callable.namespace}.${callable.name} result`)
       }
       if (callable instanceof CoercionFunction) {

packages/codemode/src/stdlib/math.ts

@@ -1,6 +1,7 @@
 export const mathConstants = new Set(["PI", "E", "LN2", "LN10", "LOG2E", "LOG10E", "SQRT2", "SQRT1_2"])
 
 export const mathMethods = new Set([
+  "random",
   "max",
   "min",
   "abs",
@@ -40,6 +41,7 @@ export const mathMethods = new Set([
 
 export const invokeMathMethod = (name: string, args: Array<unknown>, node: AstNode): number => {
   if (!mathMethods.has(name)) throw new InterpreterRuntimeError(`Math.${name} is not available in CodeMode.`, node)
+  if (name === "random") return Math.random()
   const nums = args.map((arg) => {
     if (typeof arg !== "number") throw new InterpreterRuntimeError(`Math.${name} expects number arguments.`, node)
     return arg

packages/codemode/src/stdlib/number.ts

@@ -1,6 +1,15 @@
-export const numberMethods = new Set(["toFixed", "toPrecision", "toExponential", "toString"])
+export const numberMethods = new Set(["toFixed", "toPrecision", "toExponential", "toString", "valueOf"])
 
-export const numberConstants = new Set(["MAX_SAFE_INTEGER", "MIN_SAFE_INTEGER", "MAX_VALUE", "MIN_VALUE", "EPSILON"])
+export const numberConstants = new Set([
+  "MAX_SAFE_INTEGER",
+  "MIN_SAFE_INTEGER",
+  "MAX_VALUE",
+  "MIN_VALUE",
+  "EPSILON",
+  "NaN",
+  "POSITIVE_INFINITY",
+  "NEGATIVE_INFINITY",
+])
 
 export const numberStatics = new Set(["isInteger", "isFinite", "isNaN", "isSafeInteger", "parseInt", "parseFloat"])
 
@@ -32,6 +41,9 @@ export const invokeNumberMethod = (value: number, name: string, args: Array<unkn
       result = value.toString(radix)
       break
     }
+    case "valueOf":
+      result = value
+      break
     default:
       throw new InterpreterRuntimeError(`Number method '${name}' is not available in CodeMode.`, node)
   }

packages/codemode/src/stdlib/object.ts

@@ -1,6 +1,6 @@
 import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
 import { isBlockedMember } from "../tool-runtime.js"
-import { isSandboxValue, SandboxMap, SandboxSet, SandboxURLSearchParams } from "../values.js"
+import { isSandboxValue, SandboxMap, SandboxPromise, SandboxSet, SandboxURLSearchParams } from "../values.js"
 import { boundedData, coerceToString } from "./value.js"
 
 export const objectStatics = new Set(["keys", "values", "entries", "hasOwn", "assign", "fromEntries"])
@@ -10,13 +10,23 @@ export const invokeObjectMethod = (name: string, args: Array<unknown>, node: Ast
   if (!objectStatics.has(name)) throw new InterpreterRuntimeError(`Object.${name} is not available in CodeMode.`, node)
   const requireObject = (): Record<string, unknown> => {
     const input = args[0]
-    const value = boundedData(args[0], `Object.${name} input`)
     if (Array.isArray(input)) return input as unknown as Record<string, unknown>
-    if (isSandboxValue(value)) return {}
-    if (value === null || typeof value !== "object") {
-      throw new InterpreterRuntimeError(`Object.${name} expects a data object or array.`, node)
+    if (isSandboxValue(input)) return {}
+    if (input instanceof SandboxPromise) {
+      throw new InterpreterRuntimeError(
+        `Object.${name} received an un-awaited Promise; await it before inspecting the result.`,
+        node,
+        "InvalidDataValue",
+      )
     }
-    return value as Record<string, unknown>
+    if (input === null || typeof input !== "object") {
+      throw new InterpreterRuntimeError(`Object.${name} expects a data object or array.`, node, "InvalidDataValue")
+    }
+    const prototype = Object.getPrototypeOf(input)
+    if (prototype !== null && prototype !== Object.prototype) {
+      throw new InterpreterRuntimeError(`Object.${name} expects a data object or array.`, node, "InvalidDataValue")
+    }
+    return input as Record<string, unknown>
   }
   const guardedSet = (out: Record<string, unknown>, key: string, item: unknown): void => {
     if (isBlockedMember(key)) throw new InterpreterRuntimeError(`Property '${key}' is not available in CodeMode.`, node)
@@ -28,15 +38,8 @@ export const invokeObjectMethod = (name: string, args: Array<unknown>, node: Ast
     guardedSet(out, coerceToString(key), item)
   }
   switch (name) {
-    case "keys": {
-      const value = boundedData(args[0], "Object.keys input")
-      if (isSandboxValue(value)) return []
-      if (Array.isArray(value)) return Object.keys(value)
-      if (value === null || typeof value !== "object") {
-        throw new InterpreterRuntimeError("Object.keys expects a data object or array.", node)
-      }
-      return Object.keys(value)
-    }
+    case "keys":
+      return Object.keys(requireObject())
     case "values":
       return Object.values(requireObject())
     case "entries":

packages/codemode/src/tool-runtime.ts

@@ -617,6 +617,7 @@ export const prepare = <R>(tools: HostTools<R>, catalogBudget = defaultCatalogBu
     "",
     "Use common JavaScript data operations, functions, control flow, selected standard-library methods, and awaited tool calls. Built-ins include Date, RegExp, Map, Set, URL, URLSearchParams, and URI encoding helpers.",
     "Modules/imports, classes, generators, timers, fetch, eval, prototype access, unlisted methods, and promise chaining are unavailable. Use Code Mode tools for external operations. Use await with try/catch.",
+    "Prefer explicit `return`; otherwise only the final top-level expression becomes the result.",
     "Dates and URLs serialize to strings at data boundaries; Map/Set/RegExp/URLSearchParams serialize to `{}`.",
   ]
 

packages/codemode/test/codemode.test.ts

@@ -658,6 +658,9 @@ describe("CodeMode public contract", () => {
     expect(instructions).toContain("URL, URLSearchParams, and URI encoding helpers")
     expect(instructions).not.toContain("host globals")
     expect(instructions).toContain("Use Code Mode tools for external operations")
+    expect(instructions).toContain(
+      "Prefer explicit `return`; otherwise only the final top-level expression becomes the result.",
+    )
     expect(instructions).toContain(
       "Dates and URLs serialize to strings at data boundaries; Map/Set/RegExp/URLSearchParams serialize to `{}`.",
     )

packages/codemode/test/promise.test.ts

@@ -245,6 +245,12 @@ describe("promises at data boundaries", () => {
     expect(diagnostic.message).toContain("await tools.ns.tool(...)")
   })
 
+  test("collection helpers do not let un-awaited promises cross the result boundary", async () => {
+    const diagnostic = await error(`return Array.from([Promise.resolve(1)])`)
+    expect(diagnostic.kind).toBe("InvalidDataValue")
+    expect(diagnostic.message).toContain("un-awaited Promise")
+  })
+
   test("passing an un-awaited promise as a tool argument is a clear diagnostic", async () => {
     const diagnostic = await error(`return await tools.host.sleepy({ id: tools.host.sleepy({ id: 1 }) })`)
     expect(diagnostic.kind).toBe("InvalidDataValue")

packages/codemode/test/stdlib.test.ts

@@ -19,6 +19,28 @@ const error = async (code: string) => {
   return result.error
 }
 
+describe("Number and Math", () => {
+  test("Math.random returns a number in [0, 1)", async () => {
+    expect(await value(`const n = Math.random(); return typeof n === "number" && n >= 0 && n < 1`)).toBe(true)
+  })
+
+  test("Number exposes native non-finite constants", async () => {
+    expect(
+      await value(
+        `return [Number.isNaN(Number.NaN), Number.POSITIVE_INFINITY === Infinity, Number.NEGATIVE_INFINITY === -Infinity]`,
+      ),
+    ).toEqual([true, true, true])
+  })
+
+  test("Number valueOf returns its primitive receiver", async () => {
+    expect(await value(`return (42).valueOf()`)).toBe(42)
+  })
+
+  test("Number valueOf does not enable boxed numbers", async () => {
+    expect((await error(`return new Number(42)`)).kind).toBe("UnsupportedSyntax")
+  })
+})
+
 describe("Date", () => {
   test("Date.now() returns a number", async () => {
     expect(await value(`return typeof Date.now()`)).toBe("number")
@@ -751,6 +773,43 @@ describe("sandbox values at intra-sandbox checkpoints", () => {
     )
   })
 
+  test("Object.values/entries preserve nested object identity", async () => {
+    expect(
+      await value(`
+      const child = { selected: false }
+      const rows = { a: child }
+      Object.values(rows)[0].selected = true
+      return child.selected
+    `),
+    ).toBe(true)
+    expect(
+      await value(`
+      const child = { selected: false }
+      const rows = { a: child }
+      Object.entries(rows)[0][1].selected = true
+      return child.selected
+    `),
+    ).toBe(true)
+  })
+
+  test("Object enumeration preserves promises and callable references", async () => {
+    expect(
+      await value(`
+      const pending = Promise.resolve(1)
+      const source = { pending }
+      return [Object.keys(source), Object.hasOwn(source, "pending"), await Object.values(source)[0], await Object.entries(source)[0][1]]
+    `),
+    ).toEqual([["pending"], true, 1, 1])
+    expect(await value(`return Object.values({ max: Math.max })[0](1, 2)`)).toBe(2)
+  })
+
+  test("Object enumeration rejects invalid receivers and gives promises an await hint", async () => {
+    const diagnostic = await error(`return Object.keys(Promise.resolve({ a: 1 }))`)
+    expect(diagnostic.kind).toBe("InvalidDataValue")
+    expect(diagnostic.message).toContain("await")
+    expect((await error(`return Object.keys(Math)`)).kind).toBe("InvalidDataValue")
+  })
+
   test("Object.assign keeps Maps usable", async () => {
     expect(await value(`const merged = Object.assign({}, { m: new Map([["a", 1]]) }); return merged.m.get("a")`)).toBe(
       1,
@@ -773,6 +832,53 @@ describe("sandbox values at intra-sandbox checkpoints", () => {
     expect(await value(`return Array.from([new Date(5)])[0].getTime()`)).toBe(5)
   })
 
+  test("Array.from and Array.of preserve nested object identity", async () => {
+    expect(
+      await value(`
+      const child = { selected: false }
+      Array.from([child])[0].selected = true
+      return child.selected
+    `),
+    ).toBe(true)
+    expect(
+      await value(`
+      const child = { selected: false }
+      Array.of(child)[0].selected = true
+      return child.selected
+    `),
+    ).toBe(true)
+  })
+
+  test("Array.from and Array.of preserve promises and callable references", async () => {
+    expect(
+      await value(`
+      const pending = Promise.resolve(1)
+      return [await Array.from([pending])[0], await Array.of(pending)[0]]
+    `),
+    ).toEqual([1, 1])
+    expect(await value(`return [Array.from([Math.max])[0](1, 2), Array.of(Math.max)[0](3, 4)]`)).toEqual([2, 4])
+  })
+
+  test("Array.from preserves identity across supported collection shapes", async () => {
+    expect(
+      await value(`
+      const child = { selected: false }
+      const fromArrayLike = Array.from({ 0: child, length: 1 })
+      const fromMap = Array.from(new Map([["child", child]]))
+      const fromSet = Array.from(new Set([child]))
+      fromArrayLike[0].selected = true
+      return [fromMap[0][1] === child, fromSet[0] === child, child.selected]
+    `),
+    ).toEqual([true, true, true])
+  })
+
+  test("Array.from rejects invalid receivers and gives promises an await hint", async () => {
+    const diagnostic = await error(`return Array.from(Promise.resolve([1]))`)
+    expect(diagnostic.kind).toBe("InvalidDataValue")
+    expect(diagnostic.message).toContain("await")
+    expect((await error(`return Array.from(() => 1)`)).kind).toBe("InvalidDataValue")
+  })
+
   test("regexes stay callable through Object.values", async () => {
     expect(await value(`return Object.values({ r: /ab+/ })[0].test("abb")`)).toBe(true)
   })

packages/core/src/mcp/client.ts

@@ -3,7 +3,7 @@ export * as MCPClient from "./client"
 import path from "node:path"
 import { execFile } from "node:child_process"
 import { pathToFileURL } from "node:url"
-import { Client, type ClientOptions } from "@modelcontextprotocol/sdk/client/index.js"
+import { Client } from "@modelcontextprotocol/sdk/client/index.js"
 import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
 import { UnauthorizedError, type OAuthClientProvider } from "@modelcontextprotocol/sdk/client/auth.js"
@@ -21,6 +21,7 @@ import {
   ListToolsResultSchema,
   PromptListChangedNotificationSchema,
   PromptSchema,
+  ResourceListChangedNotificationSchema,
   type LoggingMessageNotification,
   LoggingMessageNotificationSchema,
   ToolListChangedNotificationSchema,
@@ -68,11 +69,13 @@ export interface ToolDefinition {
 export interface PromptDefinition {
   readonly name: string
   readonly description: string | undefined
-  readonly arguments: ReadonlyArray<{
-    readonly name: string
-    readonly description: string | undefined
-    readonly required: boolean | undefined
-  }> | undefined
+  readonly arguments:
+    | ReadonlyArray<{
+        readonly name: string
+        readonly description: string | undefined
+        readonly required: boolean | undefined
+      }>
+    | undefined
 }
 
 export interface PromptMessage {
@@ -84,6 +87,28 @@ export interface PromptResult {
   readonly messages: ReadonlyArray<PromptMessage>
 }
 
+export interface ResourceDefinition {
+  readonly name: string
+  readonly uri: string
+  readonly description: string | undefined
+  readonly mimeType: string | undefined
+}
+
+export interface ResourceTemplateDefinition {
+  readonly name: string
+  readonly uriTemplate: string
+  readonly description: string | undefined
+  readonly mimeType: string | undefined
+}
+
+export type ResourceContentPart =
+  | { readonly type: "text"; readonly uri: string; readonly text: string; readonly mimeType: string | undefined }
+  | { readonly type: "blob"; readonly uri: string; readonly blob: string; readonly mimeType: string | undefined }
+
+export interface ReadResourceResult {
+  readonly contents: ReadonlyArray<ResourceContentPart>
+}
+
 export type CallToolContent =
   | { readonly type: "text"; readonly text: string }
   | { readonly type: "media"; readonly data: string; readonly mimeType: string }
@@ -124,6 +149,12 @@ export interface Connection {
   readonly tools: () => Effect.Effect<ToolDefinition[], Error>
   /** Lists the server's prompts; returns [] when the server doesn't advertise prompt support, fails on a transport error. */
   readonly prompts: () => Effect.Effect<PromptDefinition[], Error>
+  /** Lists the server's resources; returns [] when the server doesn't advertise resource support. */
+  readonly resources: () => Effect.Effect<ResourceDefinition[], Error>
+  /** Lists the server's resource templates; returns [] when the server doesn't advertise resource support. */
+  readonly resourceTemplates: () => Effect.Effect<ResourceTemplateDefinition[], Error>
+  /** Reads one resource; returns undefined when the server doesn't advertise resource support. */
+  readonly readResource: (input: { readonly uri: string }) => Effect.Effect<ReadResourceResult | undefined, Error>
   /** Invokes a prompt on the server. Interruption aborts the in-flight request. */
   readonly prompt: (input: {
     readonly name: string
@@ -141,6 +172,8 @@ export interface Connection {
   readonly onToolsChanged: (callback: () => void) => void
   /** Registers a callback fired when the server announces its prompt list changed; no-op if unsupported. */
   readonly onPromptsChanged: (callback: () => void) => void
+  /** Registers a callback fired when the server announces its resource catalog changed. */
+  readonly onResourcesChanged: (callback: () => void) => void
 }
 
 /** Connects an MCP server; closing the calling scope tears down the transport and any spawned process. */
@@ -168,7 +201,8 @@ export const connect = Effect.fnUntraced(function* (
         },
       })
     }
-    if (!URL.canParse(config.url)) return yield* new ConnectError({ server, message: `Invalid MCP URL for "${server}"` })
+    if (!URL.canParse(config.url))
+      return yield* new ConnectError({ server, message: `Invalid MCP URL for "${server}"` })
     return new StreamableHTTPClientTransport(new URL(config.url), {
       requestInit: config.headers ? { headers: config.headers } : undefined,
       authProvider,
@@ -202,10 +236,7 @@ export const connect = Effect.fnUntraced(function* (
   }).pipe(Effect.exit)
   if (Exit.isSuccess(exit)) {
     yield* Effect.addFinalizer(() =>
-      cleanupStdioDescendants(transport).pipe(
-        Effect.andThen(Effect.promise(() => client.close())),
-        Effect.ignore,
-      ),
+      cleanupStdioDescendants(transport).pipe(Effect.andThen(Effect.promise(() => client.close())), Effect.ignore),
     )
     const catalogTimeout = config.timeout?.catalog ?? DEFAULT_CATALOG_TIMEOUT
     const executionTimeout = config.timeout?.execution ?? DEFAULT_EXECUTION_TIMEOUT
@@ -257,7 +288,9 @@ export const connect = Effect.fnUntraced(function* (
               ),
             catch: (error) => (error instanceof Error ? error : new Error(String(error))),
           }).pipe(
-            Effect.tapError((error) => Effect.logWarning("failed to list MCP prompts", { server, error: error.message })),
+            Effect.tapError((error) =>
+              Effect.logWarning("failed to list MCP prompts", { server, error: error.message }),
+            ),
           )
           return prompts.map((prompt) => ({
             name: prompt.name,
@@ -269,6 +302,74 @@ export const connect = Effect.fnUntraced(function* (
             })),
           }))
         }),
+      resources: () =>
+        Effect.gen(function* () {
+          if (!client.getServerCapabilities()?.resources) return []
+          const resources = yield* Effect.tryPromise({
+            try: () =>
+              paginate(
+                (cursor) =>
+                  client.listResources(cursor === undefined ? undefined : { cursor }, { timeout: catalogTimeout }),
+                (result) => result.resources,
+              ),
+            catch: (error) => (error instanceof Error ? error : new Error(String(error))),
+          }).pipe(
+            Effect.tapError((error) =>
+              Effect.logWarning("failed to list MCP resources", { server, error: error.message }),
+            ),
+          )
+          return resources.map((resource) => ({
+            name: resource.name,
+            uri: resource.uri,
+            description: resource.description,
+            mimeType: resource.mimeType,
+          }))
+        }),
+      resourceTemplates: () =>
+        Effect.gen(function* () {
+          if (!client.getServerCapabilities()?.resources) return []
+          const templates = yield* Effect.tryPromise({
+            try: () =>
+              paginate(
+                (cursor) =>
+                  client.listResourceTemplates(cursor === undefined ? undefined : { cursor }, {
+                    timeout: catalogTimeout,
+                  }),
+                (result) => result.resourceTemplates,
+              ),
+            catch: (error) => (error instanceof Error ? error : new Error(String(error))),
+          }).pipe(
+            Effect.tapError((error) =>
+              Effect.logWarning("failed to list MCP resource templates", { server, error: error.message }),
+            ),
+          )
+          return templates.map((template) => ({
+            name: template.name,
+            uriTemplate: template.uriTemplate,
+            description: template.description,
+            mimeType: template.mimeType,
+          }))
+        }),
+      readResource: (input) =>
+        Effect.gen(function* () {
+          if (!client.getServerCapabilities()?.resources) return undefined
+          const result = yield* Effect.tryPromise({
+            try: (signal) => client.readResource({ uri: input.uri }, { signal, timeout: executionTimeout }),
+            catch: (error) => (error instanceof Error ? error : new Error(String(error))),
+          }).pipe(
+            Effect.tapError((error) =>
+              Effect.logWarning("failed to read MCP resource", { server, uri: input.uri, error: error.message }),
+            ),
+          )
+          return {
+            contents: result.contents.map(
+              (part): ResourceContentPart =>
+                "text" in part
+                  ? { type: "text", uri: part.uri, text: part.text, mimeType: part.mimeType }
+                  : { type: "blob", uri: part.uri, blob: part.blob, mimeType: part.mimeType },
+            ),
+          }
+        }),
       prompt: (input) =>
         Effect.tryPromise({
           try: (signal) =>
@@ -328,13 +429,14 @@ export const connect = Effect.fnUntraced(function* (
         if (!client.getServerCapabilities()?.prompts?.listChanged) return
         client.setNotificationHandler(PromptListChangedNotificationSchema, async () => callback())
       },
+      onResourcesChanged: (callback) => {
+        if (!client.getServerCapabilities()?.resources?.listChanged) return
+        client.setNotificationHandler(ResourceListChangedNotificationSchema, async () => callback())
+      },
     } satisfies Connection
   }
 
-  yield* cleanupStdioDescendants(transport).pipe(
-    Effect.andThen(Effect.promise(() => transport.close())),
-    Effect.ignore,
-  )
+  yield* cleanupStdioDescendants(transport).pipe(Effect.andThen(Effect.promise(() => transport.close())), Effect.ignore)
   const error = Cause.squash(exit.cause)
   if (error instanceof UnauthorizedError) return yield* new NeedsAuthError({ server })
   return yield* new ConnectError({ server, message: error instanceof Error ? error.message : String(error) })

packages/core/src/mcp/index.ts

@@ -83,48 +83,16 @@ export class PromptResult extends Schema.Class<PromptResult>("MCP.PromptResult")
   messages: Schema.Array(PromptMessage),
 }) {}
 
-export class Resource extends Schema.Class<Resource>("MCP.Resource")({
-  server: ServerName,
-  name: Schema.String,
-  uri: Schema.String,
-  description: Schema.String.pipe(Schema.optional),
-  mimeType: Schema.String.pipe(Schema.optional),
-}) {}
-
-export class ResourceTemplate extends Schema.Class<ResourceTemplate>("MCP.ResourceTemplate")({
-  server: ServerName,
-  name: Schema.String,
-  uriTemplate: Schema.String,
-  description: Schema.String.pipe(Schema.optional),
-  mimeType: Schema.String.pipe(Schema.optional),
-}) {}
-
-export class ResourceCatalog extends Schema.Class<ResourceCatalog>("MCP.ResourceCatalog")({
-  resources: Schema.Array(Resource),
-  templates: Schema.Array(ResourceTemplate),
-}) {}
-
-export const ResourceContentPart = Schema.Union([
-  Schema.Struct({
-    type: Schema.Literal("text"),
-    uri: Schema.String,
-    text: Schema.String,
-    mimeType: Schema.String.pipe(Schema.optional),
-  }),
-  Schema.Struct({
-    type: Schema.Literal("blob"),
-    uri: Schema.String,
-    blob: Schema.String,
-    mimeType: Schema.String.pipe(Schema.optional),
-  }),
-]).pipe(Schema.toTaggedUnion("type"))
-export type ResourceContentPart = typeof ResourceContentPart.Type
-
-export class ResourceContent extends Schema.Class<ResourceContent>("MCP.ResourceContent")({
-  server: ServerName,
-  uri: Schema.String,
-  contents: Schema.Array(ResourceContentPart),
-}) {}
+export const Resource = Mcp.Resource
+export type Resource = Mcp.Resource
+export const ResourceTemplate = Mcp.ResourceTemplate
+export type ResourceTemplate = Mcp.ResourceTemplate
+export const ResourceCatalog = Mcp.ResourceCatalog
+export type ResourceCatalog = Mcp.ResourceCatalog
+export const ResourceContentPart = Mcp.ResourceContentPart
+export type ResourceContentPart = Mcp.ResourceContentPart
+export const ResourceContent = Mcp.ResourceContent
+export type ResourceContent = Mcp.ResourceContent
 
 export class NotFoundError extends Schema.TaggedErrorClass<NotFoundError>()("MCP.NotFoundError", {
   server: ServerName,
@@ -415,6 +383,24 @@ export const layer = Layer.effect(
         ),
       })
 
+    const toResource = (server: ServerName, def: MCPClient.ResourceDefinition) =>
+      Resource.make({
+        server,
+        name: def.name,
+        uri: def.uri,
+        description: def.description,
+        mimeType: def.mimeType,
+      })
+
+    const toResourceTemplate = (server: ServerName, def: MCPClient.ResourceTemplateDefinition) =>
+      ResourceTemplate.make({
+        server,
+        name: def.name,
+        uriTemplate: def.uriTemplate,
+        description: def.description,
+        mimeType: def.mimeType,
+      })
+
     const refreshTools = (name: ServerName, entry: ServerEntry, connection: MCPClient.Connection) =>
       connection.tools().pipe(
         Effect.map((defs) => {
@@ -443,6 +429,7 @@ export const layer = Layer.effect(
         entry.prompts = undefined
         entry.status = { status: "failed", error: "Connection closed" }
         fork(events.publish(McpEvent.ToolsChanged, { server: name }).pipe(Effect.ignore))
+        fork(events.publish(McpEvent.ResourcesChanged, { server: name }).pipe(Effect.ignore))
         fork(events.publish(Command.Event.Updated, {}).pipe(Effect.ignore))
         fork(events.publish(McpEvent.StatusChanged, { server: name }).pipe(Effect.ignore))
       })
@@ -458,6 +445,10 @@ export const layer = Layer.effect(
       connection.onPromptsChanged(() => {
         fork(refreshPrompts(name, entry, connection).pipe(Effect.ignore))
       })
+      connection.onResourcesChanged(() => {
+        if (entry.client !== connection) return
+        fork(events.publish(McpEvent.ResourcesChanged, { server: name }).pipe(Effect.ignore))
+      })
     }
 
     const serverLog = (server: ServerName, message: MCPClient.LogMessage) => {
@@ -501,6 +492,7 @@ export const layer = Layer.effect(
           // after the initial registration sweep and emits no list-changed notification would otherwise
           // stay invisible to the model.
           yield* events.publish(McpEvent.ToolsChanged, { server: name }).pipe(Effect.ignore)
+          yield* events.publish(McpEvent.ResourcesChanged, { server: name }).pipe(Effect.ignore)
           yield* events.publish(McpEvent.StatusChanged, { server: name }).pipe(Effect.ignore)
           fork(refreshPrompts(name, entry, result.value.connection).pipe(Effect.ignore))
           return
@@ -557,11 +549,6 @@ export const layer = Layer.effect(
       concurrency: "unbounded",
       discard: true,
     })
-    const gate = Effect.fnUntraced(function* (server: ServerName | string) {
-      const target = yield* requireServer(server)
-      yield* Deferred.await(target.entry.startup)
-    })
-
     return Service.of({
       servers: Effect.fn("MCP.servers")(function* () {
         const entries = Array.from(runtime).toSorted(([a], [b]) => a.localeCompare(b))
@@ -637,11 +624,54 @@ export const layer = Layer.effect(
       }),
       resourceCatalog: Effect.fn("MCP.resourceCatalog")(function* () {
         yield* whenAllReady
-        return new ResourceCatalog({ resources: [], templates: [] })
+        const catalogs = yield* Effect.forEach(
+          Array.from(runtime),
+          ([name, entry]) => {
+            if (!entry.client) return Effect.succeed({ resources: [], templates: [] })
+            return Effect.all(
+              {
+                resources: entry.client.resources().pipe(Effect.catch(() => Effect.succeed([]))),
+                templates: entry.client.resourceTemplates().pipe(Effect.catch(() => Effect.succeed([]))),
+              },
+              { concurrency: "unbounded" },
+            ).pipe(
+              Effect.map((catalog) => ({
+                resources: catalog.resources.map((def) => toResource(name, def)),
+                templates: catalog.templates.map((def) => toResourceTemplate(name, def)),
+              })),
+            )
+          },
+          { concurrency: "unbounded" },
+        )
+        return ResourceCatalog.make({
+          resources: catalogs
+            .flatMap((catalog) => catalog.resources)
+            .toSorted(
+              (a, b) => a.server.localeCompare(b.server) || a.name.localeCompare(b.name) || a.uri.localeCompare(b.uri),
+            ),
+          templates: catalogs
+            .flatMap((catalog) => catalog.templates)
+            .toSorted(
+              (a, b) =>
+                a.server.localeCompare(b.server) ||
+                a.name.localeCompare(b.name) ||
+                a.uriTemplate.localeCompare(b.uriTemplate),
+            ),
+        })
       }),
       readResource: Effect.fn("MCP.readResource")(function* (input) {
-        yield* gate(input.server)
-        return undefined
+        const target = yield* requireServer(input.server)
+        yield* Deferred.await(target.entry.startup)
+        if (!target.entry.client) return undefined
+        const result = yield* target.entry.client
+          .readResource({ uri: input.uri })
+          .pipe(Effect.catch(() => Effect.succeed(undefined)))
+        if (!result) return undefined
+        return ResourceContent.make({
+          server: target.name,
+          uri: input.uri,
+          contents: result.contents,
+        })
       }),
     })
   }),

packages/core/src/session.ts

@@ -243,6 +243,7 @@ export interface Interface {
     text: string
     description?: string
     metadata?: Record<string, unknown>
+    resume?: boolean
   }) => Effect.Effect<void, NotFoundError>
   readonly revert: {
     readonly stage: (input: {
@@ -682,6 +683,7 @@ const layer = Layer.effect(
           description: input.description,
           metadata: input.metadata,
         })
+        if (input.resume === false) return
         yield* execution
           .resume(input.sessionID)
           .pipe(Effect.ignore, Effect.forkIn(scope, { startImmediately: true }), Effect.asVoid)

packages/core/test/fixture/mcp-timeout.ts

@@ -4,16 +4,27 @@ import {
   CallToolRequestSchema,
   GetPromptRequestSchema,
   ListPromptsRequestSchema,
+  ListResourcesRequestSchema,
+  ListResourceTemplatesRequestSchema,
   ListToolsRequestSchema,
+  ReadResourceRequestSchema,
 } from "@modelcontextprotocol/sdk/types.js"
 
-const server = new Server({ name: "timeout", version: "1.0.0" }, { capabilities: { prompts: {}, tools: {} } })
+const server = new Server(
+  { name: "timeout", version: "1.0.0" },
+  { capabilities: { prompts: {}, resources: {}, tools: {} } },
+)
 
 server.setRequestHandler(ListToolsRequestSchema, async () => {
   if (process.env.MCP_TIMEOUT_TARGET === "catalog") await Bun.sleep(100)
   return { tools: [{ name: "slow", inputSchema: { type: "object" } }] }
 })
 server.setRequestHandler(ListPromptsRequestSchema, () => Promise.resolve({ prompts: [{ name: "slow" }] }))
+server.setRequestHandler(ListResourcesRequestSchema, async () => {
+  if (process.env.MCP_TIMEOUT_TARGET === "resource-catalog") await Bun.sleep(100)
+  return { resources: [{ name: "slow", uri: "test://slow" }] }
+})
+server.setRequestHandler(ListResourceTemplatesRequestSchema, () => Promise.resolve({ resourceTemplates: [] }))
 server.setRequestHandler(CallToolRequestSchema, async () => {
   await Bun.sleep(100)
   return { content: [] }
@@ -22,5 +33,9 @@ server.setRequestHandler(GetPromptRequestSchema, async () => {
   await Bun.sleep(100)
   return { messages: [] }
 })
+server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
+  await Bun.sleep(100)
+  return { contents: [{ uri: request.params.uri, text: "slow" }] }
+})
 
 await server.connect(new StdioServerTransport())

packages/core/test/fixture/mcp.ts

@@ -14,15 +14,12 @@ export const emptyMcpLayer = Layer.succeed(
     instructions: () => Effect.succeed([]),
     prompts: () => Effect.succeed([]),
     prompt: () => Effect.succeed(undefined),
-    resourceCatalog: () => Effect.succeed(new MCP.ResourceCatalog({ resources: [], templates: [] })),
+    resourceCatalog: () => Effect.succeed(MCP.ResourceCatalog.make({ resources: [], templates: [] })),
     readResource: () => Effect.succeed(undefined),
   }),
 )
 
-export const emptyConfigLayer = Layer.succeed(
-  Config.Service,
-  Config.Service.of({ entries: () => Effect.succeed([]) }),
-)
+export const emptyConfigLayer = Layer.succeed(Config.Service, Config.Service.of({ entries: () => Effect.succeed([]) }))
 
 export const testLocationLayer = Layer.succeed(
   Location.Service,

packages/core/test/mcp.test.ts

@@ -3,26 +3,165 @@ import { describe, expect, test } from "bun:test"
 import { Client } from "@modelcontextprotocol/sdk/client/index.js"
 import { InMemoryTransport } from "@modelcontextprotocol/sdk/inMemory.js"
 import { Server } from "@modelcontextprotocol/sdk/server/index.js"
-import { CallToolRequestSchema, ListToolsRequestSchema } from "@modelcontextprotocol/sdk/types.js"
+import { WebStandardStreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/webStandardStreamableHttp.js"
+import {
+  CallToolRequestSchema,
+  ListResourcesRequestSchema,
+  ListResourceTemplatesRequestSchema,
+  ListToolsRequestSchema,
+  ReadResourceRequestSchema,
+} from "@modelcontextprotocol/sdk/types.js"
 import { ConfigMCP } from "@opencode-ai/core/config/mcp"
+import { Config } from "@opencode-ai/core/config"
+import { Credential } from "@opencode-ai/core/credential"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { EventV2 } from "@opencode-ai/core/event"
+import { Form } from "@opencode-ai/core/form"
+import { Integration } from "@opencode-ai/core/integration"
+import { Location } from "@opencode-ai/core/location"
 import { MCP } from "@opencode-ai/core/mcp/index"
 import { MCPClient } from "@opencode-ai/core/mcp/client"
 import { PermissionV2 } from "@opencode-ai/core/permission"
+import { AbsolutePath } from "@opencode-ai/core/schema"
 import { SessionV2 } from "@opencode-ai/core/session"
 import { McpTool } from "@opencode-ai/core/tool/mcp"
 import { ToolRegistry } from "@opencode-ai/core/tool/registry"
 import { ToolOutputStore } from "@opencode-ai/core/tool-output-store"
-import { Deferred, Effect, Fiber, Layer, Stream } from "effect"
+import { Deferred, Effect, Exit, Fiber, Layer, Stream } from "effect"
 import { testEffect } from "./lib/effect"
+import { location } from "./fixture/location"
 import { settleTool, toolDefinitions, toolIdentity, waitForTool } from "./lib/tool"
 
 let assertion: Deferred.Deferred<PermissionV2.AssertInput> | undefined
 let decision: Effect.Effect<void, PermissionV2.Error> = Effect.void
 let calls = 0
 
+type ResourcePage = {
+  items: Array<{ name: string; uri: string; description?: string; mimeType?: string }>
+  nextCursor?: string
+}
+
+type ResourceTemplatePage = {
+  items: Array<{ name: string; uriTemplate: string; description?: string; mimeType?: string }>
+  nextCursor?: string
+}
+
+function resourceServer(input: { resources?: boolean; listChanged?: boolean } = {}) {
+  return Effect.acquireRelease(
+    Effect.promise(async () => {
+      const state = {
+        resources: [] as ResourcePage["items"],
+        templates: [] as ResourceTemplatePage["items"],
+        resourcePages: undefined as Record<string, ResourcePage> | undefined,
+        templatePages: undefined as Record<string, ResourceTemplatePage> | undefined,
+        contents: [
+          { uri: "docs://readme", text: "hello", mimeType: "text/plain" },
+          { uri: "docs://logo", blob: "aGVsbG8=", mimeType: "image/png" },
+        ] as Array<{ uri: string; text: string; mimeType?: string } | { uri: string; blob: string; mimeType?: string }>,
+        resourceLists: 0,
+        templateLists: 0,
+      }
+      const protocol = new Server(
+        { name: "mcp-resources", version: "1.0.0" },
+        {
+          capabilities: {
+            tools: {},
+            ...(input.resources === false ? {} : { resources: { listChanged: input.listChanged } }),
+          },
+        },
+      )
+      protocol.setRequestHandler(ListToolsRequestSchema, () => Promise.resolve({ tools: [] }))
+      if (input.resources !== false) {
+        protocol.setRequestHandler(ListResourcesRequestSchema, (request) => {
+          state.resourceLists += 1
+          const page = state.resourcePages?.[request.params?.cursor ?? "initial"]
+          return Promise.resolve({ resources: page?.items ?? state.resources, nextCursor: page?.nextCursor })
+        })
+        protocol.setRequestHandler(ListResourceTemplatesRequestSchema, (request) => {
+          state.templateLists += 1
+          const page = state.templatePages?.[request.params?.cursor ?? "initial"]
+          return Promise.resolve({ resourceTemplates: page?.items ?? state.templates, nextCursor: page?.nextCursor })
+        })
+        protocol.setRequestHandler(ReadResourceRequestSchema, () => Promise.resolve({ contents: state.contents }))
+      }
+      const transport = new WebStandardStreamableHTTPServerTransport({
+        sessionIdGenerator: () => crypto.randomUUID(),
+        enableJsonResponse: true,
+      })
+      await protocol.connect(transport)
+      const http = Bun.serve({
+        port: 0,
+        fetch: (request) => transport.handleRequest(request),
+      })
+      return {
+        state,
+        url: http.url.toString(),
+        sendResourceListChanged: () => protocol.sendResourceListChanged(),
+        close: async () => {
+          await protocol.close().catch(() => {})
+          await http.stop(true)
+        },
+      }
+    }),
+    (server) => Effect.promise(server.close),
+  )
+}
+
+function resourceMcpLayer(url: string) {
+  const directory = AbsolutePath.make(import.meta.dir)
+  const unusedIntegration = () => Effect.die("unused integration service")
+  return MCP.layer.pipe(
+    Layer.provide(
+      Layer.mergeAll(
+        Layer.succeed(
+          Config.Service,
+          Config.Service.of({
+            entries: () =>
+              Effect.succeed([
+                new Config.Document({
+                  type: "document",
+                  info: new Config.Info({
+                    mcp: new ConfigMCP.Info({
+                      servers: { resources: new ConfigMCP.Remote({ type: "remote", url, oauth: false }) },
+                    }),
+                  }),
+                }),
+              ]),
+          }),
+        ),
+        Layer.succeed(Location.Service, Location.Service.of(location({ directory }))),
+        Layer.mock(EventV2.Service, {
+          subscribe: () => Stream.never,
+          publish: (definition, data) =>
+            Effect.succeed({
+              id: EventV2.ID.create(),
+              type: definition.type,
+              data,
+            } as EventV2.Payload<typeof definition>),
+        }),
+        Layer.mock(Form.Service, {}),
+        Layer.mock(Integration.Service, {
+          connection: {
+            active: unusedIntegration,
+            resolve: unusedIntegration,
+            key: unusedIntegration,
+            oauth: unusedIntegration,
+            update: unusedIntegration,
+            remove: unusedIntegration,
+          },
+          attempt: {
+            status: unusedIntegration,
+            complete: unusedIntegration,
+            cancel: unusedIntegration,
+          },
+        }),
+        Layer.mock(Credential.Service, {}),
+      ),
+    ),
+  )
+}
+
 const mcp = Layer.mock(MCP.Service, {
   tools: () =>
     Effect.succeed([
@@ -241,6 +380,163 @@ test("applies the configured MCP execution timeout to prompts", async () => {
   await expect(result).rejects.toThrow("Request timed out")
 })
 
+test("applies configured MCP timeouts to resource operations", async () => {
+  const catalog = Effect.runPromise(
+    Effect.scoped(
+      Effect.gen(function* () {
+        const connection = yield* MCPClient.connect(
+          "resource-catalog-timeout",
+          new ConfigMCP.Local({
+            type: "local",
+            command: [process.execPath, path.join(import.meta.dir, "fixture/mcp-timeout.ts")],
+            environment: { MCP_TIMEOUT_TARGET: "resource-catalog" },
+            timeout: new ConfigMCP.Timeout({ catalog: 10 }),
+          }),
+          import.meta.dir,
+        )
+        return yield* connection.resources()
+      }),
+    ),
+  )
+  await expect(catalog).rejects.toThrow("Request timed out")
+
+  const read = Effect.runPromise(
+    Effect.scoped(
+      Effect.gen(function* () {
+        const connection = yield* MCPClient.connect(
+          "resource-read-timeout",
+          new ConfigMCP.Local({
+            type: "local",
+            command: [process.execPath, path.join(import.meta.dir, "fixture/mcp-timeout.ts")],
+            timeout: new ConfigMCP.Timeout({ execution: 10 }),
+          }),
+          import.meta.dir,
+        )
+        return yield* connection.readResource({ uri: "test://slow" })
+      }),
+    ),
+  )
+  await expect(read).rejects.toThrow("Request timed out")
+})
+
+test("lists, reads, and reports MCP resource changes", async () => {
+  await Effect.runPromise(
+    Effect.scoped(
+      Effect.gen(function* () {
+        const server = yield* resourceServer({ listChanged: true })
+        server.state.resourcePages = {
+          initial: {
+            items: [{ name: "Readme", uri: "docs://readme", description: "Project docs" }],
+            nextCursor: "resources-2",
+          },
+          "resources-2": { items: [{ name: "Logo", uri: "docs://logo", mimeType: "image/png" }] },
+        }
+        server.state.templatePages = {
+          initial: {
+            items: [{ name: "File", uriTemplate: "docs://{path}" }],
+            nextCursor: "templates-2",
+          },
+          "templates-2": { items: [{ name: "Issue", uriTemplate: "issue://{id}", description: "Issue" }] },
+        }
+        const connection = yield* MCPClient.connect(
+          "resources",
+          new ConfigMCP.Remote({ type: "remote", url: server.url, oauth: false }),
+          import.meta.dir,
+        )
+
+        expect(yield* connection.resources()).toEqual([
+          { name: "Readme", uri: "docs://readme", description: "Project docs", mimeType: undefined },
+          { name: "Logo", uri: "docs://logo", description: undefined, mimeType: "image/png" },
+        ])
+        expect(yield* connection.resourceTemplates()).toEqual([
+          { name: "File", uriTemplate: "docs://{path}", description: undefined, mimeType: undefined },
+          { name: "Issue", uriTemplate: "issue://{id}", description: "Issue", mimeType: undefined },
+        ])
+        expect(yield* connection.readResource({ uri: "docs://readme" })).toEqual({
+          contents: [
+            { type: "text", uri: "docs://readme", text: "hello", mimeType: "text/plain" },
+            { type: "blob", uri: "docs://logo", blob: "aGVsbG8=", mimeType: "image/png" },
+          ],
+        })
+
+        const changed = yield* Deferred.make<void>()
+        connection.onResourcesChanged(() => Deferred.doneUnsafe(changed, Exit.void))
+        yield* Effect.promise(server.sendResourceListChanged)
+        yield* Deferred.await(changed)
+      }),
+    ),
+  )
+})
+
+test("skips MCP resource requests when the capability is absent", async () => {
+  await Effect.runPromise(
+    Effect.scoped(
+      Effect.gen(function* () {
+        const server = yield* resourceServer({ resources: false })
+        const connection = yield* MCPClient.connect(
+          "resources",
+          new ConfigMCP.Remote({ type: "remote", url: server.url, oauth: false }),
+          import.meta.dir,
+        )
+        expect(yield* connection.resources()).toEqual([])
+        expect(yield* connection.resourceTemplates()).toEqual([])
+        expect(yield* connection.readResource({ uri: "docs://readme" })).toBeUndefined()
+        expect({ resources: server.state.resourceLists, templates: server.state.templateLists }).toEqual({
+          resources: 0,
+          templates: 0,
+        })
+      }),
+    ),
+  )
+})
+
+test("loads and reads MCP resources", async () => {
+  await Effect.runPromise(
+    Effect.scoped(
+      Effect.gen(function* () {
+        const server = yield* resourceServer()
+        server.state.resources = [{ name: "Readme", uri: "docs://readme" }]
+        server.state.templates = [{ name: "File", uriTemplate: "docs://{path}" }]
+
+        yield* Effect.gen(function* () {
+          const service = yield* MCP.Service
+          expect(yield* service.resourceCatalog()).toEqual({
+            resources: [
+              {
+                server: "resources",
+                name: "Readme",
+                uri: "docs://readme",
+                description: undefined,
+                mimeType: undefined,
+              },
+            ],
+            templates: [
+              {
+                server: "resources",
+                name: "File",
+                uriTemplate: "docs://{path}",
+                description: undefined,
+                mimeType: undefined,
+              },
+            ],
+          })
+
+          server.state.resources = [{ name: "Guide", uri: "docs://guide" }]
+          expect((yield* service.resourceCatalog()).resources.map((resource) => resource.uri)).toEqual(["docs://guide"])
+          expect(yield* service.readResource({ server: "resources", uri: "docs://readme" })).toEqual({
+            server: "resources",
+            uri: "docs://readme",
+            contents: [
+              { type: "text", uri: "docs://readme", text: "hello", mimeType: "text/plain" },
+              { type: "blob", uri: "docs://logo", blob: "aGVsbG8=", mimeType: "image/png" },
+            ],
+          })
+        }).pipe(Effect.provide(resourceMcpLayer(server.url)))
+      }),
+    ),
+  )
+})
+
 it.effect("advertises MCP output schemas to Code Mode", () =>
   Effect.gen(function* () {
     const registry = yield* ToolRegistry.Service

packages/protocol/src/groups/mcp.ts

@@ -19,4 +19,18 @@ export const McpGroup = HttpApiGroup.make("server.mcp")
         }),
       ),
   )
-  .annotateMerge(OpenApi.annotations({ title: "mcp", description: "MCP server status routes." }))
+  .add(
+    HttpApiEndpoint.get("mcp.resource.catalog", "/api/mcp/resource", {
+      query: LocationQuery,
+      success: Location.response(Mcp.ResourceCatalog),
+    })
+      .annotateMerge(locationQueryOpenApi)
+      .annotateMerge(
+        OpenApi.annotations({
+          identifier: "v2.mcp.resource.catalog",
+          summary: "List MCP resources",
+          description: "Retrieve resources and resource templates from connected MCP servers.",
+        }),
+      ),
+  )
+  .annotateMerge(OpenApi.annotations({ title: "mcp", description: "MCP server and resource routes." }))

packages/protocol/src/groups/session.ts

@@ -344,6 +344,7 @@ export const makeSessionGroup = <I extends HttpApiMiddleware.AnyId, S>(sessionLo
           text: Schema.String,
           description: Schema.String.pipe(Schema.optional),
           metadata: SessionMessage.Synthetic.fields.metadata,
+          resume: Schema.Boolean.pipe(Schema.optional),
         }),
         success: HttpApiSchema.NoContent,
         error: SessionNotFoundError,

packages/protocol/test/event.test.ts

@@ -4,5 +4,6 @@ import { isOpenCodeEvent } from "../src/groups/event.js"
 test("classifies public events by type", () => {
   expect(isOpenCodeEvent({ type: "server.connected" })).toBe(true)
   expect(isOpenCodeEvent({ type: "mcp.status.changed" })).toBe(true)
+  expect(isOpenCodeEvent({ type: "mcp.resources.changed" })).toBe(true)
   expect(isOpenCodeEvent({ type: "mcp.tools.changed" })).toBe(false)
 })

packages/schema/src/event-manifest.ts

@@ -80,6 +80,7 @@ export const ServerDefinitions = Event.inventory(
   ...InstallationEvent.Definitions,
   ...VcsEvent.Definitions,
   McpEvent.StatusChanged,
+  McpEvent.ResourcesChanged,
   // Shared transitional: V1 contracts the current TUI still consumes during
   // the migration (permission.asked/replied, question.asked, session.error).
   // Remove when the TUI moves to the current permission/question surfaces.

packages/schema/src/index.ts

@@ -9,6 +9,7 @@ export { Form } from "./form.js"
 export { Integration } from "./integration.js"
 export { LLM } from "./llm.js"
 export { Location } from "./location.js"
+export { Mcp } from "./mcp.js"
 export { Model } from "./model.js"
 export { Permission } from "./permission.js"
 export { PermissionSaved } from "./permission-saved.js"

packages/schema/src/mcp-event.ts

@@ -10,6 +10,13 @@ export const ToolsChanged = Event.ephemeral({
   },
 })
 
+export const ResourcesChanged = Event.ephemeral({
+  type: "mcp.resources.changed",
+  schema: {
+    server: Schema.String,
+  },
+})
+
 export const BrowserOpenFailed = Event.ephemeral({
   type: "mcp.browser.open.failed",
   schema: {
@@ -27,4 +34,4 @@ export const StatusChanged = Event.ephemeral({
   },
 })
 
-export const Definitions = Event.inventory(ToolsChanged, StatusChanged)
+export const Definitions = Event.inventory(ToolsChanged, ResourcesChanged, StatusChanged)

packages/schema/src/mcp.ts

@@ -25,14 +25,9 @@ const NeedsClientRegistration = Schema.Struct({
 }).annotate({ identifier: "Mcp.Status.NeedsClientRegistration" })
 
 export type Status = typeof Status.Type
-export const Status = Schema.Union([
-  Connected,
-  Pending,
-  Disabled,
-  Failed,
-  NeedsAuth,
-  NeedsClientRegistration,
-]).pipe(Schema.toTaggedUnion("status"))
+export const Status = Schema.Union([Connected, Pending, Disabled, Failed, NeedsAuth, NeedsClientRegistration]).pipe(
+  Schema.toTaggedUnion("status"),
+)
 
 export interface Server extends Schema.Schema.Type<typeof Server> {}
 export const Server = Schema.Struct({
@@ -42,3 +37,50 @@ export const Server = Schema.Struct({
   // without matching by name, which could collide with provider or plugin integrations.
   integrationID: optional(IntegrationID),
 }).annotate({ identifier: "Mcp.Server" })
+
+export interface Resource extends Schema.Schema.Type<typeof Resource> {}
+export const Resource = Schema.Struct({
+  server: Schema.String,
+  name: Schema.String,
+  uri: Schema.String,
+  description: optional(Schema.String),
+  mimeType: optional(Schema.String),
+}).annotate({ identifier: "Mcp.Resource" })
+
+export interface ResourceTemplate extends Schema.Schema.Type<typeof ResourceTemplate> {}
+export const ResourceTemplate = Schema.Struct({
+  server: Schema.String,
+  name: Schema.String,
+  uriTemplate: Schema.String,
+  description: optional(Schema.String),
+  mimeType: optional(Schema.String),
+}).annotate({ identifier: "Mcp.ResourceTemplate" })
+
+export interface ResourceCatalog extends Schema.Schema.Type<typeof ResourceCatalog> {}
+export const ResourceCatalog = Schema.Struct({
+  resources: Schema.Array(Resource),
+  templates: Schema.Array(ResourceTemplate),
+}).annotate({ identifier: "Mcp.ResourceCatalog" })
+
+export const ResourceContentPart = Schema.Union([
+  Schema.Struct({
+    type: Schema.Literal("text"),
+    uri: Schema.String,
+    text: Schema.String,
+    mimeType: optional(Schema.String),
+  }),
+  Schema.Struct({
+    type: Schema.Literal("blob"),
+    uri: Schema.String,
+    blob: Schema.String,
+    mimeType: optional(Schema.String),
+  }),
+]).pipe(Schema.toTaggedUnion("type"), Schema.annotate({ identifier: "Mcp.ResourceContentPart" }))
+export type ResourceContentPart = typeof ResourceContentPart.Type
+
+export interface ResourceContent extends Schema.Schema.Type<typeof ResourceContent> {}
+export const ResourceContent = Schema.Struct({
+  server: Schema.String,
+  uri: Schema.String,
+  contents: Schema.Array(ResourceContentPart),
+}).annotate({ identifier: "Mcp.ResourceContent" })

packages/schema/test/contract-hygiene.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test"
 import { DateTime, Schema } from "effect"
 import { Agent } from "../src/agent.js"
 import { FileSystem } from "../src/filesystem.js"
+import { Mcp } from "../src/mcp.js"
 import { Model } from "../src/model.js"
 import { Project } from "../src/project.js"
 import { Provider } from "../src/provider.js"
@@ -51,6 +52,11 @@ describe("contract hygiene", () => {
     const identifiers = [
       Agent.Color,
       FileSystem.Submatch,
+      Mcp.Resource,
+      Mcp.ResourceTemplate,
+      Mcp.ResourceCatalog,
+      Mcp.ResourceContentPart,
+      Mcp.ResourceContent,
       Model.Ref,
       Model.Capabilities,
       Model.Cost,

packages/schema/test/event-manifest.test.ts

@@ -51,6 +51,7 @@ describe("public event manifest", () => {
     expect(EventManifest.Latest.get("agent.updated")).toBe(Agent.Event.Updated)
     expect(EventManifest.Latest.get("plugin.updated")).toBe(Plugin.Event.Updated)
     expect(EventManifest.Server.get("mcp.status.changed")).toBe(McpEvent.StatusChanged)
+    expect(EventManifest.Server.get("mcp.resources.changed")).toBe(McpEvent.ResourcesChanged)
     expect(EventManifest.Server.get("session.deleted")).toBe(SessionEvent.Deleted)
     expect(EventManifest.Server.has("mcp.tools.changed")).toBe(false)
     expect(Agent.Event.Updated.durable).toBeUndefined()
@@ -76,7 +77,7 @@ describe("public event manifest", () => {
     expect(Form.Event.Definitions).toEqual([Form.Event.Created, Form.Event.Replied, Form.Event.Cancelled])
     expect(Reference.Event.Definitions).toEqual([Reference.Event.Updated])
     expect(Plugin.Event.Definitions).toEqual([Plugin.Event.Added, Plugin.Event.Updated])
-    expect(McpEvent.Definitions).toEqual([McpEvent.ToolsChanged, McpEvent.StatusChanged])
+    expect(McpEvent.Definitions).toEqual([McpEvent.ToolsChanged, McpEvent.ResourcesChanged, McpEvent.StatusChanged])
     expect(EventManifest.Latest.has("mcp.browser.open.failed")).toBe(false)
     expect(EventManifest.Latest.has("ide.installed")).toBe(false)
     expect(IdeEvent.Definitions).toEqual([IdeEvent.Installed])

packages/schema/test/mcp.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, test } from "bun:test"
+import { Schema } from "effect"
+import { Mcp } from "../src/mcp.js"
+
+describe("Mcp resources", () => {
+  test("decodes resource catalogs and omits absent metadata", () => {
+    const value = Schema.decodeUnknownSync(Mcp.ResourceCatalog)({
+      resources: [{ server: "docs", name: "Readme", uri: "docs://readme" }],
+      templates: [{ server: "docs", name: "File", uriTemplate: "docs://{path}" }],
+    })
+
+    expect(Schema.encodeSync(Mcp.ResourceCatalog)(value)).toEqual({
+      resources: [{ server: "docs", name: "Readme", uri: "docs://readme" }],
+      templates: [{ server: "docs", name: "File", uriTemplate: "docs://{path}" }],
+    })
+  })
+
+  test("preserves text and base64 blob contents", () => {
+    expect(
+      Schema.decodeUnknownSync(Mcp.ResourceContent)({
+        server: "docs",
+        uri: "docs://readme",
+        contents: [
+          { type: "text", uri: "docs://readme", text: "hello", mimeType: "text/plain" },
+          { type: "blob", uri: "docs://logo", blob: "aGVsbG8=", mimeType: "image/png" },
+        ],
+      }),
+    ).toEqual({
+      server: "docs",
+      uri: "docs://readme",
+      contents: [
+        { type: "text", uri: "docs://readme", text: "hello", mimeType: "text/plain" },
+        { type: "blob", uri: "docs://logo", blob: "aGVsbG8=", mimeType: "image/png" },
+      ],
+    })
+  })
+})

packages/server/src/handlers/mcp.ts

@@ -6,20 +6,28 @@ import { response } from "../location"
 
 export const McpHandler = HttpApiBuilder.group(Api, "server.mcp", (handlers) =>
   Effect.gen(function* () {
-    return handlers.handle(
-      "mcp.list",
-      Effect.fn(function* () {
-        const service = yield* MCP.Service
-        return yield* response(
-          service
-            .servers()
-            .pipe(
-              Effect.map((servers) =>
-                servers.map((info) => ({ name: info.name, status: info.status, integrationID: info.integrationID })),
+    return handlers
+      .handle(
+        "mcp.list",
+        Effect.fn(function* () {
+          const service = yield* MCP.Service
+          return yield* response(
+            service
+              .servers()
+              .pipe(
+                Effect.map((servers) =>
+                  servers.map((info) => ({ name: info.name, status: info.status, integrationID: info.integrationID })),
+                ),
               ),
-            ),
-        )
-      }),
-    )
+          )
+        }),
+      )
+      .handle(
+        "mcp.resource.catalog",
+        Effect.fn(function* () {
+          const service = yield* MCP.Service
+          return yield* response(service.resourceCatalog())
+        }),
+      )
   }),
 )

packages/server/src/handlers/session.ts

@@ -329,6 +329,7 @@ export const SessionHandler = HttpApiBuilder.group(Api, "server.session", (handl
               text: ctx.payload.text,
               description: ctx.payload.description,
               metadata: ctx.payload.metadata,
+              resume: ctx.payload.resume,
             })
             .pipe(
               Effect.catchTag("Session.NotFoundError", (error) =>